PRAGUE — Czech citizens joined their leaders and foreign politicians Sunday in paying tribute to Vaclav Havel, the dissident playwright who led the 1989 Velvet Revolution that peacefully toppled communism in the former Czechoslovakia.

A black flag flew over Prague Castle, the presidential seat, while Czechs lighted candles at the monument to the 1989 Velvet Revolution in downtown Prague in memory of Mr. Havel, who died earlier Sunday at the age of 75. Others came to his villa in Prague to lay flowers and light candles.

Vaclav Klaus, Mr. Havel’s political archrival who replaced him as president in 2003, called Mr. Havel “the symbol of the new era of the Czech state.”

In Washington, President Obama said he was “deeply saddened” by Mr. Havel’s death.

“His peaceful resistance shook the foundations of an empire, exposed the emptiness of a repressive ideology and proved that moral leadership is more powerful than any weapon,” Mr. Obama said.

In neighboring Poland, former President Lech Walesa, the founder of the anti-communist Solidarity movement, called Mr. Havel “a great fighter for the freedom of nations and for democracy.”

“It is a great pity and a great loss. His outstanding voice of wisdom will be missed in Europe,” said Mr. Walesa, the 1983 Nobel Peace Prize laureate.

Shy and bookish, with a wispy mustache and unkempt hair, Mr. Havel, a dissident playwright, was an unlikely hero of Czechoslovakia’s 1989 “Velvet Revolution” after four decades of suffocating repression.

He was his country’s first democratically elected president. He led it through the early challenges of democracy and its peaceful 1993 breakup into the Czech Republic and Slovakia, though his image suffered as his people discovered the difficulties of transforming their society.

Mr. Havel first made a name for himself after the 1968 Soviet-led invasion that crushed the Prague Spring reforms of Alexander Dubcek and other liberally minded communists in what was then Czechoslovakia.

His plays were banned, as hard-liners installed by Moscow snuffed out every whiff of rebellion.

Born Oct. 5, 1936, in Prague, the child of a wealthy family that lost extensive property to communist nationalization in 1948, Mr. Havel was denied a formal education, eventually earning a degree at night school and starting out in theater as a stagehand.

His political activism began in earnest in January 1977, when he co-authored the human rights manifesto Charter 77. The cause drew widening attention in the West.

Mr. Havel was detained countless times and spent four years in communist jails.

The events of August 1988, the 20th anniversary of the Warsaw Pact invasion, first suggested that Mr. Havel and his friends might one day replace the faceless apparatchiks who jailed them.

Thousands of mostly young people marched through central Prague, yelling Mr. Havel’s name.

His arrest in January 1989 at another street protest and his subsequent trial generated anger at home and abroad. Pressure for change was so strong that the communists released him again in May.

That fall, communism began to collapse across Eastern Europe, and in November the Berlin Wall fell. Eight days later, communist police brutally broke up a demonstration by thousands of Prague students.

It was the signal that Mr. Havel and his country had awaited. Within 48 hours, a broad new opposition movement was founded; and a day later, hundreds of thousands of Czechs and Slovaks took to the streets.

On Dec. 29, 1989, Mr. Havel was elected Czechoslovakia’s president by the country’s still-communist parliament.

In July 1992, it became clear that the Czechoslovak federation was heading for a split. Considering it a personal failure, Mr. Havel resigned as president. However he remained popular and was elected president of the new Czech Republic uncontested.